One of the striking findings of the 1986-1987 NIDR Survey of Dental Caries of U.S. School Children was that approximately half the children ages 5-17 had never experienced caries in their permanent teeth. This study is exploring the relationship between a caries-free status ana such variables as sex, ethnicity, geographic region and urban-rural residence. Controls are the approximately 1400 children of the same ages whose cumulative caries experience exceeds two standard deviations of the mean (mean DMFS) for that age group. Preliminary analyses indicate highly significant differences among the two groups with respect to geographic region of residence. Therefore, the study was expanded to include data on ten trace metals obtained from drinking water samples from the schools attended by the subjects. Because the probability of being in the high caries group was strongly correlated with age, separate logistical regression models were fit for each year of age. Phosphorus, silicon, strontium and molybdenum were significantly (p <0.10) but weakly associated with caries status, though the relationship was inconsistent. Further models were fitted to test interactions among the independent variables. The analyses were completed and are being summarized.